If the six light poles skirting Canberra’s Manuka Oval look like they’re on a lean, that’s because they are.

The 47-metre-high lights lean inwards, because, if they were standing straight, they couldn’t be approved under the city’s RL617 rule.

The strict planning regulation wouldn’t bend, so the light poles had to.

Hitting the grass ceiling

RL617 isn’t a rule that most Canberrans would encounter on a daily basis, but developers, planners and architects know it well. It sets the maximum height for structures in Canberra’s Parliamentary Zone.

“When you look across Civic and think it’s all a bit stunted … it’s because of that,” Rodney Moss, former director of Cox Architecture, said.

The height limit under the rule is 617 metres above sea level, which is specifically set to a chosen point on the landscape — the grassy peak of Parliament House’s sloping lawns.

Parliament House was designed so that ordinary Australians could walk over its roof, putting the people literally above their parliament.

And this, among other natural vistas in the Parliamentary Zone, is exactly what RL617 was designed to protect.

In 1990, the National Capital Authority (NCA) formalised the height limit as a key urban design rule in the inaugural National Capital Plan, preserving architect Walter Burley Griffin’s vision of a bush capital, where the natural environment remains dominant over built form.

In doing so, Parliament House’s rooftop hill became the grass ceiling of the city.

Only Parliament House’s flagpole and the dome of the Australian War Memorial poke above the invisible line.

Height of the light not quite right

In 2012, when broadcast-quality lighting was being installed at Manuka Oval to enable the venue to host more night-time sporting matches, Mr Moss had a challenge on his hands.

“In order to give you television-quality light on the oval, the lights need to be a certain height,” he said.

But Mr Moss said that would have taken the lights above the limit imposed by the planning rule.

“What we did was bend the lights so that they came down below 617 metres above sea level, and then we made the light head into a shovel, so that the maximum amount of light is right on the edge,” he said.

The angled design solved the height problem, but the extra engineering required came at a price.

“If it was straight up in the air, you’ve got a footing that goes straight down. That’s OK,” Mr Moss said.

“If you’ve got this huge weight leaning forward, then the footings have to be much larger because it wants to fall over.

The city that can’t grow up?

The RL617 planning rule doesn’t apply everywhere. 

Town centres like Woden, Gungahlin and Belconnen are outside its reach, but as Canberra’s population pushes towards half a million, adapting the rule would require negotiation between the territory and the NCA.

“We’ve had a rule that has preserved a certain attitude to how the city grows, and I think it’s now time that we sit down and have an adult discussion about where the city goes in the future.

“I don’t think we’re looking for a city that climbs uniformly higher, but some activation and some punctuation points, with higher, slender buildings would be, I think, a welcome addition.

“I think there’s a discussion for the community, about what we want to see next.”

A city centre looking for an ‘urban climax’

In effect, the RL617 planning rule keeps a lid on the city skyline, as if drawing an invisible line across the horizon.

It leaves places like City Hill as places of unrealised potential according to Ms Townsend, especially as its surrounding buildings near completion.

And while she doesn’t believe City Hill itself should have buildings on it, Ms Townsend said its heritage-listed trees currently functioned like a stage curtain, blocking the vista to the south.

She has a vision of a landscape and skyline that better reflects Canberra today.

“What are we going to do with City Hill? What do we think about raising the height limits in the city to provide a more exciting and larger-scale expression of, ‘We have arrived at the centre of the city’?”

It’s a thought Mr Moss shares.

He said the RL617 rule explained what many locals and visitors had noticed but couldn’t quite put their finger on.

“Canberra is lacking in urban climax,” he said.

“You sort of drive in and you think, ‘Where is it?’”